What Is Sildenafil?

Sildenafil relaxes muscles found in the walls of blood vessels and increases blood flow to particular areas of the body. Sildenafil under the name Viagra is used to treat erectile dysfunction (impotence) in men. Another brand of sildenafil is Revatio, which is used to treat pulmonary arterial hypertension and improve exercise capacity in men and women. Do not take Viagra while also taking Revatio, unless your doctor tells you to.

Important information
Do not take sildenafil if you are also using a nitrate drug for chest pain or heart problems, including nitroglycerin, isosorbide dinitrate, isosorbide mononitrate, and some recreational drugs such as “poppers”. Taking sildenafil with a nitrate medicine can cause a sudden and serious decrease in blood pressure. Some medicines can cause unwanted or dangerous effects when used with sildenafil. Tell your doctor about all your current medicines, especially riociguat (Adempas). Contact your doctor or seek emergency medical attention if your erection is painful or lasts longer than 4 hours. A prolonged erection (priapism) can damage the penis. Stop using sildenafil and get emergency medical help if you have sudden vision loss.

Before taking this medicine
You should not use sildenafil if you are allergic to it, or:

if you take other medicines to treat pulmonary arterial hypertension, such as riociguat (Adempas).

Do not take sildenafil if you are also using a nitrate drug for chest pain or heart problems. This includes nitroglycerin, isosorbide dinitrate, and isosorbide mononitrate. Nitrates are also found in some recreational drugs such as amyl nitrate or nitrite (“poppers”). Taking sildenafil with a nitrate medicine can cause a sudden and serious decrease in blood pressure.

To make sure sildenafil is safe for you, tell your doctor about your other medical conditions, especially:

heart disease or heart rhythm problems, coronary artery disease;

a recent history (in the past 6 months) of a heart attack, stroke, or congestive heart failure;

high or low blood pressure;

liver or kidney disease;

a blood cell disorder such as sickle cell anemia, multiple myeloma, or leukemia;

a bleeding disorder such as hemophilia;

a stomach ulcer;

retinitis pigmentosa (an inherited condition of the eye);

a physical deformity of the penis (such as Peyronie’s disease); or

if you have been told you should not have sexual intercourse for health reasons.

Sildenafil can decrease blood flow to the optic nerve of the eye, causing sudden vision loss. This has occurred in a small number of people taking sildenafil, most of whom also had heart disease, diabetes, high blood pressure, high cholesterol, or certain pre-existing eye problems, and in those who smoked or were over 50 years old. It is not clear whether sildenafil is the actual cause of vision loss.

This medicine is not expected to harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant.

It is not known whether sildenafil passes into breast milk or if it could harm a nursing baby. Tell your doctor if you are breast-feeding a baby.

Do not give sildenafil to anyone under 18 years old without medical advice.

How Should I Take Sildenafil?

Take sildenafil exactly as it was prescribed for you Follow all directions on your prescription label. Do not take this medicine in larger or smaller amounts or for longer than recommended.

Revatio is usually taken three times each day, about 4 to 6 hours apart.

Viagra is usually taken only when needed, 30 minutes to 1 hour before sexual activity. You may take it up to 4 hours before sexual activity. Do not take Viagra more than once per day.

Shake the oral suspension (liquid) well just before you measure a dose. Measure liquid medicine with the dosing syringe provided, or with a special dose-measuring spoon or medicine cup. If you do not have a dose-measuring device, ask your pharmacist for one.

Viagra can help you have an erection when sexual stimulation occurs. An erection will not occur just by taking a pill. Follow your doctor’s instructions.

During sexual activity, if you become dizzy or nauseated, or have pain, numbness, or tingling in your chest, arms, neck, or jaw, stop and call your doctor right away. You could be having a serious side effect of sildenafil.

Store at room temperature away from moisture and heat.

Sildenafil dosing information

1. Usual Adult Dose of Sildenafil for Erectile Dysfunction:
-Initial dose: 50 mg orally once a day, as needed, 1 hour prior to sexual activity
-Maintenance: 25 to 100 mg orally once a day, as needed, 1 hour prior to sexual activity
-Comments: This drug may be taken anywhere from 30 minutes to 4 hours before sexual activity.

What happens if I miss a dose?
Since Viagra is used as needed, you are not likely to miss a dose. If you miss a dose of Revatio, take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose.

What happens if I overdose?
Seek emergency medical attention or call the Poison Help line.

What should I avoid while taking sildenafil?
Drinking alcohol with this medicine can cause side effects. Grapefruit and grapefruit juice may interact with sildenafil and lead to unwanted side effects. Avoid the use of grapefruit products while taking sildenafil.

Avoid using any other medicines to treat impotence, such as alprostadil or yohimbine, without first talking to your doctor.

Sildenafil Side Effects

Get emergency medical help if you have signs of an allergic reaction to sildenafil: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

erection is painful or lasts longer than 4 hours (prolonged erection can damage the penis).

Call your doctor at once if you have:

ringing in your ears, or sudden hearing loss;

irregular heartbeat;

swelling in your hands, ankles, or feet;

shortness of breath;

seizure (convulsions); or

a light-headed feeling, like you might pass out.

Common sildenafil side effects may include:

flushing (warmth, redness, or tingly feeling);

headache, dizziness;

abnormal vision (blurred vision, changes in color vision)

stuffy nose;

muscle pain, back pain; or

upset stomach.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects.

What other drugs will affect sildenafil?
Do not take sildenafil with similar medications such as avanafil (Stendra), tadalafil (Cialis) or vardenafil (Levitra). Tell your doctor about all other medications you use for erectile dysfunction.

Tell your doctor about all your current medicines and any you start or stop using, especially:

an antibiotic such as clarithromycin, erythromycin, or telithromycin;

antifungal medicine such as ketoconazole or itraconazole;

medicine to treat HIV/AIDS, such as atazanavir, indinavir, ritonavir, or saquinavir; or

drugs to treat high blood pressure or a prostate disorder.

This list is not complete. Other drugs may interact with sildenafil, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible interactions are listed in this medication guide.